1. CHEM 304 – 2/1/12 I.A. Fundamentals of Atmospheric Chemistry - Concentration Units - Final word on Stability and Trace Species: “Disequilibrium” > READ CH 1: Review DG and K cal;cs from gen chem book if necessary. > Quiz M on HW #1 (& #2, Q1) – covers thru today lecture.

3. Quantifying Concentrations: Express the following as X’s (i.e. pure numbers). a) H 2 O (10km) = 36 ppm b) CH 4 (40 km) = 300ppb a) 36 ppm = 36 x 10 -6 = 3.6 x 10 -5 b) 300 ppb = 300 x 10 -9 = 3.0 x 10 -7

4. Partial pressures: Calculate the Partial Pressure of CO 2 (X CO2 = 360 ppm) at: a) 0 km (P TOT =1 atm) b) 15 km (P TOT =122 mbar) a) P CO2 = 3.6x10 -4 x 1.0 atm = 3.6 x 10 -4 atm b) P CO2 = 3.6 x 10 -4 x 122 mbar = 4.4 x 10 -5 bar

5. Number Densities: molec/cm 3 For OH, X = 6 x 10 -14, what is C in molec/cm 3 at 0 km (p=1.0atm)?  Calc p first, then multiply by:  C L = 2.7x10 19 molec/cm 3 atm C OH = 1.6 x 10 6

6. Consider the following Reaction: N 2 + ½ O 2 —> N 2 O a) Does it “go”? How do you know? b) Is “a” really a yes/no question - what quantity gives the subtle answer? c) Can we use “b” to predict the partial pressure of N 2 O? d) Does it work? (P N2O (obs) = 3.3 x10 -7 atm)

7.  H f - Energy relative to Elements ( “–” means lower E)  G f - Overall Chemical Stability relative to Elements (“–” means more stable (or less reactive)).

8. Disequilibrium The planet is not an equilibrium system. An active state of Disequilibrium is maintained by: -Sunlight -Biology (Microbes, Humans, Livestock) -Geological factors (volcanoes) -Meteorological factors (lightning)

9. Summarizing logical questions regarding “trace species” - How much is out there? how do we quantify? (Concentration Units) - What do they do ? (free radical reaction types) - Why are they out there ? Why disequilibrium? (Photochemistry, biology…) - (Still forthcoming) How long do they last ? How to we account for their concentrations? -(Chemical Kinetics)